On Jun 30, 2010, at 2:31 PM, Kingsley Idehen wrote:
David Booth wrote:
On Wed, 2010-06-30 at 14:30 -0400, Kingsley Idehen wrote:
Nathan wrote:
Pat Hayes wrote:
[ . . . ]
Surely all of the subjects as literals arguments can be countered
with 'walk round it', and further good practise could be aided by
a few simple notes on best practise for linked data etc.
IMHO an emphatic NO.
RDF is about constructing structured descriptions where "Subjects"
have Identifiers in the form of Name References (which may or many
resolve to Structured Representations of Referents carried or
borne by Descriptor Docs/Resources). An "Identifier" != Literal.
If you are in a situation where you can't or don't want to mint an
HTTP based Name, simply use a URN, it does the job.
Can you explain *why* you think literals should not be permitted as
subjects? The rationale you have given above sounds like it is
saying
that literals should not be subjects because RDF does not permit
literals to be subjects.
IMHO, RDF should allow "anyone to say anything about anything" -- not
"anyone to say anything about anything . . . except a literal".
However, if you see some specific harm in permitting statements about
literals, please tell us what that harm would be.
Harm isn't of the "breaks anything variety". It just adds ambiguity
to the process of producing structured descriptions within Web realm.
I could flip this around and ask: what makes a pure URN or other
identification schemes (that may or may not resolve to anything)
problematic?
1. There are infinitely many numbers.
2. There is no systematic convention for specifying a URN for a given
number; whereas there are such conventions, established, standardized
and widely implemented, for (literals using) XSD datatypes.
3. The datatyping mechanism in RDF was created for exactly this
purpose. To refuse to use it and insist upon developing an alternative
(especially one which would require an infinite amount of work) seems
therefore to be obtuse.
I am of the assumption that we are seeking globally unambiguous
names (which may or may not resolve) re. Web of Linked Data aspect
of Semantic Web continuum.
Quite. A typed literal is a globally unambiguous name for the datatype
value it denotes.
RDBMS engines support literal identifiers
That is a different topic. Nobody is suggesting using literals to
identify non-literal values. In RDF, the interpretation of a literal
is *fixed* by the RDF specs.
Pat Hayes
, and the consequences are:
1. Distributed RDBMS tedium -- due to object ambiguity across
Qualifier/Schema/Database, Owner, and actual Object Name (Tables,
Views, Procedures) names
2. Security problems -- users are Identified using literals instead
of proper identifiers (as demonstrated by FOAF+SSL [3] WebIDs you
can provide blockers to socially engineered RDBMS vulnerability via
verifiable identity + data access policies).
Links:
1. http://en.wikipedia.org/wiki/Identifier
2. http://en.wikipedia.org/wiki/Unique_identifier
3. http://esw.w3.org/Foaf%2Bssl
--
Regards,
Kingsley Idehen President & CEO OpenLink Software Web:
http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
------------------------------------------------------------
IHMC (850)434 8903 or (650)494 3973
40 South Alcaniz St. (850)202 4416 office
Pensacola (850)202 4440 fax
FL 32502 (850)291 0667 mobile
phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
